ABSTRACT
Theideaofisospinaroseinnuclearphysicsintheearlythirties.Heisenberg introducedanotationinwhichtheprotonandneutronweretreatedastwo componentsofanucleondoublet
(5.1)
Hedidthisoriginallybecausehewastryingtothinkabouttheforcesbetween nucleonsinnuclei,anditwasmathematicallyconvenienttowritethingsin thisnotation.Infact,hisfirstideasaboutthisweretotallywrong-hereallydidn'thavetherightideaabouttherelationbetweentheprotonandthe neutron.Hewasthinkingoftheneutronasasortoftightlyboundstateof protonandelectron,andimaginedthatforcesbetweennucleonscouldarise byexchangeofelectrons.Inthiswayyoucouldgetaforcebetweenproton andneutronbylettingtheelectronshuttlebackandforth-inanalogywith anHiion,andaforcebetweenneutronandneutron-ananalogywitha neutralH 2molecule.Butnoforcebetweenprotonandproton.
